Pathology and Monkeypox virus Localization in Tissues From Immunocompromised Patients With Severe or Fatal Mpox.

BACKGROUND: Pathology and Monkeypox virus (MPXV) tissue tropism in severe and fatal human mpox is not thoroughly described but can help elucidate the disease pathogenesis and the role of coinfections in immunocompromised patients. METHODS: We analyzed biopsy and autopsy tissues from 22 patients with severe or fatal outcomes to characterize pathology and viral antigen and DNA distribution in tissues by immunohistochemistry and in situ hybridization. Tissue-based testing for coinfections was also performed. RESULTS: Mucocutaneous lesions showed necrotizing and proliferative epithelial changes. Deceased patients with autopsy tissues evaluated had digestive tract lesions, and half had systemic tissue necrosis with thrombotic vasculopathy in lymphoid tissues, lung, or other solid organs. Half also had bronchopneumonia, and one-third had acute lung injury. All cases had MPXV antigen and DNA detected in tissues. Coinfections were identified in 5 of 16 (31%) biopsy and 4 of 6 (67%) autopsy cases. CONCLUSIONS: Severe mpox in immunocompromised patients is characterized by extensive viral infection of tissues and viremic dissemination that can progress despite available therapeutics. Digestive tract and lung involvement are common and associated with prominent histopathological and clinical manifestations. Coinfections may complicate mpox diagnosis and treatment. Significant viral DNA (likely correlating to infectious virus) in tissues necessitates enhanced biosafety measures in healthcare and autopsy settings.

Pseudomonas species may appear strikingly filamentous in tissue sections: an important consideration for surgical pathologists and a reminder of the utility of modified silver impregnation methods.

Although tissue culture is the gold standard for diagnosing infection, histologic examination of surgically resected tissue can be a critical component in the diagnosis of tissue infection. The goal of this brief report is to alert surgical pathologists that Pseudomonas species can appear strikingly filamentous histologically and may somewhat mimic the appearance of filamentous bacteria, such Actinomyces or Nocardia, or thin fungal hyphae. A secondary aim is to raise awareness that Pseudomonas can sometimes only be identified histologically through the use of a modified silver impregnation method (Steiner stain). Five cases of filamentous Pseudomonas were encountered in three different surgical pathology subspecialities (ophthalmic pathology, cardiovascular pathology, and dermatopathology) over a 1-year period. All cases were of formalin-fixed, paraffin-embedded tissue, stained using hematoxylin & eosin (H&E) and multiple histochemical stains. Four cases grew Pseudomonas aeruginosa in culture and, in the fifth case, a nonaeruginosa species was detected using polymerase chain reaction-based methods. The markedly filamentous-appearing Pseudomonas organisms were identified in five different tissue sites: vascular graft, enucleation (whole eye) specimen, scleral biopsy, soft-tissue excision, and skin punch biopsy. In one of the five cases the organisms were seen on H&E, and in only two of the five were the organisms seen on Brown-Hopps stain. In all five cases, the organisms were identified on Steiner stain. It is therefore important to recognize that Pseudomonas can appear markedly filamentous, Pseudomonas or other bacterial infection is suspected, the surgical pathologist would be advised to employ the Steiner stain to most consistently detect the organisms.

Vasculopathy and Increased Vascular Congestion in Fatal COVID-19 and Acute Respiratory Distress Syndrome.

Rationale: The leading cause of death in coronavirus disease 2019 (COVID-19) is severe pneumonia, with many patients developing acute respiratory distress syndrome (ARDS) and diffuse alveolar damage (DAD). Whether DAD in fatal COVID-19 is distinct from other causes of DAD remains unknown. Objective: To compare lung parenchymal and vascular alterations between patients with fatal COVID-19 pneumonia and other DAD-causing etiologies using a multidimensional approach. Methods: This autopsy cohort consisted of consecutive patients with COVID-19 pneumonia (n = 20) and with respiratory failure and histologic DAD (n = 21; non-COVID-19 viral and nonviral etiologies). Premortem chest computed tomography (CT) scans were evaluated for vascular changes. Postmortem lung tissues were compared using histopathological and computational analyses. Machine-learning-derived morphometric analysis of the microvasculature was performed, with a random forest classifier quantifying vascular congestion (CVasc) in different microscopic compartments. Respiratory mechanics and gas-exchange parameters were evaluated longitudinally in patients with ARDS. Measurements and Main Results: In premortem CT, patients with COVID-19 showed more dilated vasculature when all lung segments were evaluated (P = 0.001) compared with controls with DAD. Histopathology revealed vasculopathic changes, including hemangiomatosis-like changes (P = 0.043), thromboemboli (P = 0.0038), pulmonary infarcts (P = 0.047), and perivascular inflammation (P < 0.001). Generalized estimating equations revealed significant regional differences in the lung microarchitecture among all DAD-causing entities. COVID-19 showed a larger overall CVasc range (P = 0.002). Alveolar-septal congestion was associated with a significantly shorter time to death from symptom onset (P = 0.03), length of hospital stay (P = 0.02), and increased ventilatory ratio [an estimate for pulmonary dead space fraction (Vd); p = 0.043] in all cases of ARDS. Conclusions: Severe COVID-19 pneumonia is characterized by significant vasculopathy and aberrant alveolar-septal congestion. Our findings also highlight the role that vascular alterations may play in Vd and clinical outcomes in ARDS in general.

Factors associated with myocardial SARS-CoV-2 infection, myocarditis, and cardiac inflammation in patients with COVID-19.

COVID-19 has been associated with cardiac injury and dysfunction. While both myocardial inflammatory cell infiltration and myocarditis with myocyte injury have been reported in patients with fatal COVID-19, clinical-pathologic correlations remain limited. The objective was to determine the relationships between cardiac pathological changes in patients dying from COVID-19 and cardiac infection by SARS-CoV-2, laboratory measurements, clinical features, and treatments. In a retrospective study, 41 consecutive autopsies of patients with fatal COVID-19 were analyzed for the associations between cardiac inflammation, myocarditis, cardiac infection by SARS-CoV-2, clinical features, laboratory measurements, and treatments. Cardiac infection was assessed by in situ hybridization and NanoString transcriptomic profiling. Cardiac infection by SARS-CoV-2 was present in 30/41 cases: virus+ with myocarditis (n = 4), virus+ without myocarditis (n = 26), and virus- without myocarditis (n = 11). In the cases with cardiac infection, SARS-CoV-2+ cells in the myocardium were rare, with a median density of 1 cell/cm2. Virus+ cases showed higher densities of myocardial CD68+ macrophages and CD3+ lymphocytes, as well as more electrocardiographic changes (23/27 vs 4/10; P = 0.01). Myocarditis was more prevalent with IL-6 blockade than with nonbiologic immunosuppression, primarily glucocorticoids (2/3 vs 0/14; P = 0.02). Overall, SARS-CoV-2 cardiac infection was less prevalent in patients treated with nonbiologic immunosuppression (7/14 vs 21/24; P = 0.02). Myocardial macrophage and lymphocyte densities overall were positively correlated with the duration of symptoms but not with underlying comorbidities. In summary, cardiac infection with SARS-CoV-2 is common among patients dying from COVID-19 but often with only rare infected cells. Cardiac infection by SARS-CoV-2 is associated with more cardiac inflammation and electrocardiographic changes. Nonbiologic immunosuppression is associated with lower incidences of myocarditis and cardiac infection by SARS-CoV-2.

Cardiac genetic test yields and genotype-phenotype correlations from large cohort investigated by medical examiner's office.

BACKGROUND: Few reports describe the yield of postmortem genetic testing from medical examiners' offices or correlate genetic test results with autopsy-confirmed phenotypes from a large cohort. OBJECTIVES: To report results from cardiomyopathy- and cardiac arrhythmia-associated genetic testing in conjunction with autopsy findings of cases investigated at the United States' largest medical examiner office. METHODS: Postmortem cases tested from 2015 to 2022 with a cardiomyopathy- and cardiac arrhythmia-associated gene panel were reviewed. American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines were used to classify variant pathogenicity. Correlations of pathogenic/likely pathogenic variants (P/LPVs) with cardiac pathology were evaluated. RESULTS: The cohort included 1107 decedents of diverse ages and ethnicities. P/LPVs were detected in 87 (7.9%) cases, with 73 and 14 variants in cardiomyopathy and cardiac arrhythmia genes, respectively. Variants of uncertain significance were detected in 437 (39.5%) cases. The diagnostic yield (percentage of P/LPV) in decedents with cardiomyopathy (26.1%) was significantly higher than those without (P<.0001). The diagnostic yield was significantly lower in infants (0.7%) than older age groups (ranging from 1 to 74 years old, 5.7%-25.9%), which had no statistical difference between their yields. The diagnostic yields by cardiac autopsy findings were 54.0% for hypertrophic cardiomyopathy, 47.1% for arrhythmogenic cardiomyopathy, 20.0% for myocardial fibrosis, 19.0% for dilated cardiomyopathy, and 11.3% for myocarditis. Most P/LPVs were in MYBPC3, TTN, PKP2, SCN5A, MYH7, and FLNC. Ten P/LPVs were novel. CONCLUSIONS: Our results support the importance of performing postmortem genetic testing on decedents of all ages with cardiomyopathy, cardiac lesions insufficient to diagnosis a specific cardiomyopathy (e.g., myocardial fibrosis), and myocarditis. Combined postmortem cardiac examination and genetic analysis are advantageous in accurately determining the underlying cause of death and informing effective clinical care of family members.

The Eyes Have It: How Critical are Ophthalmic Findings to the Diagnosis of Pediatric Abusive Head Trauma?

Pediatric abusive head trauma (AHT), still colloquially known as shaken baby syndrome, is a leading cause of morbidity and mortality among infants. Controversy has grown surrounding this diagnosis, and the specificity of the clinical findings-subdural hemorrhage, cerebral edema, and retinal hemorrhages-has been challenged. A literature search of peer reviewed publications on PubMed pertaining to the history, clinical, and pathologic features of AHT was conducted using the terms "shaken baby syndrome," "non-accidental trauma," "abusive head trauma," "inflicted traumatic brain injury," "shaken impact syndrome," and "whiplash shaken infant syndrome." Focus was placed on articles discussing ophthalmic findings in AHT. Retinal hemorrhages-particularly those that are too numerous to count, occurring in all layers of the retina (preretinal, intraretinal, subretinal), covering the peripheral pole and extending to the ora serrata, and accompanied by retinoschisis and other ocular/periocular hemorrhages-are highly suggestive of AHT, particularly in the absence of otherwise explained massive accidental trauma. Although the diagnosis has grown in controversy in recent years, AHT has well-documented clinical and pathologic findings across a large number of studies.

Patient-facing communication for cytopathologists: A framework for disclosing diagnostic error.

Medical errors are a major source of harm to patients. Regulatory bodies mandate and patient safety experts advocate the disclosure of medical errors to patients to promote transparency and to create accountability for improving health care processes. Although pathologists regularly report errors-either to pathology or clinical colleagues or via internal safety reporting systems-few pathologists directly disclose those errors to patients. Yet many pathologists are interested in participating in the direct disclosure of medical errors to patients and may even be mandated to do so. When surveyed on why they do not directly disclose errors to patients, pathologists commonly cite a lack of confidence and a lack of training. Another barrier cited is the lack of a preexisting relationship between the pathologist and the patient. With respect to this last barrier, cytopathologists have a distinct advantage over surgical or clinical pathologists, as many cytopathologists regularly interact with and develop a rapport with patients when they are performing fine-needle aspiration (FNA) procedures. To improve the safety culture in pathology, direct error disclosure practices must be developed, supported, and strengthened. It is critical for cytopathologists to be comfortable with disclosing errors to patients. Being comfortable with disclosing an error, however, requires training, practice, and advance reflection. Using a practical, case-based format centered around FNA examples, this article addresses how to disclose a medical error to a patient. It provides a framework, heuristic principles, and structured conversation systems and talking points to guide the inexperienced pathologist to find his or her voice in a challenging disclosure conversation.

The next phase in patient safety education: Towards a standardized, tools-based pathology patient safety curriculum: A call to action from the Association of Pathology Chairs' Residency Program Directors Section Training Residents in Patient Safety Workgroup.

Patient safety education is a mandated Common Program Requirement of the Accreditation Council for Graduate Medical Education and for the Royal College of Physicians and Surgeons of Canada in all medical residency and fellowship programs. Although many hospitals and healthcare environments have general patient safety education tools for trainees, few to none focus on the unique training milieu of pathologists, including a mix of highly automated and manual error-prone processes, frequent multiplicity of events, and lack of direct patient relationships for error disclosure. We established a national Association of Pathology Chairs-Program Directors Section Workgroup focused on patient safety education for pathology trainees entitled Training Residents in Patient Safety (TRIPS). TRIPS included diverse representatives from across the United States, as well as representatives from pathology organizations including the American Board of Pathology, the American Society for Clinical Pathology, the United States and Canadian Academy of Pathology, the College of American Pathologists, and the Society to Improve Diagnosis in Medicine. Objectives of the workgroup included developing a standardized patient safety curriculum, designing teaching and assessment tools, and refining them with pilot sites. Here we report the establishment of TRIPS as well as data from national needs assessment of Program Directors across the country, who confirmed the need for a standardized patient safety curriculum.

Pathology trainees rarely report safety incidents: A review of 13,722 safety reports and a call to action.

Reporting and understanding patient safety incidents is a cornerstone of improving patient care quality and safety. The Accreditation Council for Graduate Medical Education specifically mandates that physician trainee education include participation in the recognition, reporting, and root cause analysis of patient safety incidents. Studies on safety event reporting, however, have consistently shown that attending physicians submit few safety reports, and trainees submit even fewer. We undertook a study to assess the rate at which pathology trainees report patient safety events relative to the rates at which trainees in other medical specialties do. We performed a retrospective analysis of 13,722 safety reports submitted to our medium-sized Academic Medical Center's incident reporting system. We then analyzed those reported by trainees (residents and fellows), and then further drilled down on the subset of trainee-reported safety events reported by pathology trainees. Despite accounting for over 5% of all types of trainees at the enterprise level, pathology trainees accounted for only 0.5% of all trainee safety reports. Our findings represent a call to action for pathology training programs to engage their residents and fellows in quality and safety initiatives, to understand and remove barriers to safety event reporting for vulnerable populations such as trainees, and to empower trainees to confidently report safety risks as valued frontline care providers.

Changes in Surgical Pathology Case Volume and Amendment Rates During the COVID-19 Pandemic.

OBJECTIVES: Surgical pathology volume decreased during the peak of the coronavirus disease 2019 (COVID-19) pandemic. We looked at the 4 months with the greatest reduction in surgical pathology volume during the COVID-19 pandemic and compared them with those same months in 2019 to determine changes in specimen volume. We compared the amendment rates during those periods and types of amendments issued (identification [ID], report defect [RD], diagnostic information [DI]). METHODS: All pathology reports between March to June 2019 and March to June 2020 were extracted from the pathology information system. All amendments issued were extracted over the same period and then subclassified by two pathologists. RESULTS: There was a 52.1% reduction in surgical pathology volume between the 4-month periods in 2019 and 2020 (P = .04). The amendment rate was 0.9% in 2019 compared with 1.4% in 2020, representing a 65.5% increase in amendments overall. There was a 53.3% reduction in amendments issued for ID, a 3.8% reduction in RD, and a 23.2% increase in amendments issued for DI. The change in amendments was not statistically significant. CONCLUSIONS: These findings suggest that a reduction in workload would not improve error rates. The circumstances of the pandemic highlight the many factors contributing to error rates in surgical pathology.

Prioritizing Patient Safety and Minimizing Waste: Institutional Review of Cases and a Proposed Process for Designing a Surgical Pathology Gross-Only Examination Policy.

OBJECTIVES: Gross-only examination policies vary widely across pathology departments. Several studies-particularly a College of American Pathologists' Q-Probes study-have looked at the variations in gross-only policies, and even more studies have addressed the (in)appropriateness of certain specimen types for gross-only examination. Few, if any, studies have tackled the important task of how to revise and safely implement a new gross-only examination protocol, especially in collaboration with clinical colleagues. METHODS: We reviewed the grossing protocols from three anatomic pathology centers to identify common gross-only specimen types. We compiled an inclusive list of any specimen types that appeared on one or more centers' lists. We performed a retrospective review of the gross and microscopic diagnoses for those specimen types to determine if any diagnoses of significance would have been missed had that specimen been processed as a gross-only. RESULTS: We reviewed 940 cases among 13 specimen types. For 7 specimen types, the gross diagnoses provided equivalent information to the microscopic diagnoses. For 6 specimen types, microscopic diagnoses provided clinically meaningful information beyond what was captured in the gross diagnoses. CONCLUSIONS: To improve the value of care provided, pathology departments should conduct internal reviews and consider transitioning specimen types to gross-only when safe.

Towards high reliability in national pathology education: Evaluating the United States and Canadian Academy of Pathology educational product.

The United States and Canadian Academy of Pathology (USCAP) leadership undertook a high level, global review of educational product outcomes data using high reliability organization (HRO) principles: preoccupation with failure; reluctance to simplify; sensitivity to operations; commitment to resilience; and deference to expertise. HRO principles have long been applied to fields such as aviation, nuclear power, and more recently to healthcare, yet they are rarely applied to the field that underpins these-and many other-complex systems: education. While errors in education are less calamitous than in air travel or healthcare delivery, USCAP's educational products impact over 15,000 learners a year, and thus have important implications for the future practice of pathology. Here we report USCAP's experiences using HRO principles to evaluate our keystone educational product, the "USCAP Short Course." Following this novel method of data review, USCAP leadership was able to better understand diverse learner needs based on practice venue, training level, and course topic. Unexpected lessons included the identification of specifically challenging educational topics, such as molecular pathology, and a need to focus more resources on emerging fields such as quality and patient safety. The results allow USCAP to assess educational product performance using HRO tools, and provide strong data-driven decision support for future national pathology education strategy.

Bone Marrow and Peripheral Blood Findings in Patients Infected by SARS-CoV-2.

OBJECTIVES: Coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is associated with diverse clinical, including hematologic, abnormalities. We describe peripheral blood and bone marrow findings in deceased and living patients with COVID-19. METHODS: We examined bone marrows from 20 autopsies and 2 living patients with COVID-19 using H&E-stained slides and immunohistochemical stains. Clinical history and laboratory values were reviewed. HScore was calculated to estimate risk of hemophagocytic lymphohistocytosis (HLH). RESULTS: The deceased patients included 12 men and 8 women (aged 32 to >89 years; median, 63 years). Hematologic abnormalities included frequent neutrophilic leukocytosis, lymphopenia, anemia, and thrombocytopenia; one patient showed striking erythrocytosis. The bone marrows were all normocellular to hypercellular, most showing maturing trilineage hematopoiesis with myeloid left shift. In all 19 evaluable bone marrows, hemophagocytic histiocytes were identified. The HScore for secondary HLH ranged from 35 to 269 (median, 125; >169 in 5 patients). Coinfections were identified in 6 patients. In 2 living patients, bone marrow showed maturing trilineage hematopoiesis, including one showing few hemophagocytic histiocytes. CONCLUSIONS: Peripheral blood from deceased patients with COVID-19 frequently showed neutrophilic leukocytosis, lymphopenia, and, rarely, secondary polycythemia; hemophagocytosis was common in their bone marrow. Consistent with other studies, we provide histopathologic evidence of secondary HLH development in patients with COVID-19.

Comparison of RNA In Situ Hybridization and Immunohistochemistry Techniques for the Detection and Localization of SARS-CoV-2 in Human Tissues.

Coronavirus disease-19 (COVID-19) is caused by a newly discovered coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although SARS-CoV-2 is visualized on electron microscopy, there is an increasing demand for widely applicable techniques to visualize viral components within tissue specimens. Viral protein and RNA can be detected on formalin-fixed paraffin-embedded (FFPE) tissue using immunohistochemistry (IHC) and in situ hybridization (ISH), respectively. Herein, we evaluate the staining performance of ISH for SARS-CoV-2 and an IHC directed at the SARS-CoV nucleocapsid protein and compare these results to a gold standard, tissue quantitative real-time polymerase chain reaction (qRT-PCR). We evaluated FFPE sections from 8 COVID-19 autopsies, including 19 pulmonary and 39 extrapulmonary samples including the heart, liver, kidney, small intestine, skin, adipose tissue, and bone marrow. We performed RNA-ISH for SARS-CoV-2 on all cases with IHC for SARS-CoV and SARS-CoV-2 qRT-PCR performed on selected cases. Lungs from 37 autopsies performed before the COVID-19 pandemic served as negative controls. The ISH and IHC slides were reviewed by 4 observers to record a consensus opinion. Selected ISH and IHC slides were also reviewed by 4 independent observers. Evidence of SARS-CoV-2 was identified on both the IHC and ISH platforms. Within the postmortem lung, detected viral protein and RNA were often extracellular, predominantly within hyaline membranes in patients with diffuse alveolar damage. Among individual cases, there was regional variation in the amount of detectable virus in lung samples. Intracellular viral RNA and protein was localized to pneumocytes and immune cells. Viral RNA was detected on RNA-ISH in 13 of 19 (68%) pulmonary FFPE blocks from patients with COVID-19. Viral protein was detected on IHC in 8 of 9 (88%) pulmonary FFPE blocks from patients with COVID-19, although in 5 cases the stain was interpreted as equivocal. From the control cohort, FFPE blocks from all 37 patients were negative for SARS-CoV-2 RNA-ISH, whereas 5 of 13 cases were positive on IHC. Collectively, when compared with qRT-PCR on individual tissue blocks, the sensitivity and specificity for ISH was 86.7% and 100%, respectively, while those for IHC were 85.7% and 53.3%, respectively. The interobserver variability for ISH ranged from moderate to almost perfect, whereas that for IHC ranged from slight to moderate. All extrapulmonary samples from COVID-19-positive cases were negative for SARS-CoV-2 by ISH, IHC, and qRT-PCR. SARS-CoV-2 is detectable on both RNA-ISH and nucleocapsid IHC. In the lung, viral RNA and nucleocapsid protein is predominantly extracellular and within hyaline membranes in some cases, while intracellular locations are more prominent in others. The intracellular virus is detected within pneumocytes, bronchial epithelial cells, and possibly immune cells. The ISH platform is more specific, easier to analyze and the interpretation is associated with the improved interobserver agreement. ISH, IHC, and qRT-PCR failed to detect the virus in the heart, liver, and kidney.

Predictors of Recurrence and Survival in Patients With Surgically Resected Pancreatic Neuroendocrine Tumors.

OBJECTIVE: Given the lack of consensus on surveillance guidelines after pancreatic neuroendocrine tumor (PanNET) resection, we assessed outcomes in a large cohort of patients with nonmetastatic, surgically resected PanNETs. METHODS: Data of patients with PanNETs resected between 1990 and 2017 were retrospectively collected using databases at 3 academic institutions. The National Death Index was queried to determine vital status. Kaplan-Meier analysis was used to estimate recurrence-free survival (RFS) and disease-specific survival (DSS) rates. Variables associated with recurrence and disease-related death were identified through Cox multivariate analyses. RESULTS: Of 307 patients with PanNET who underwent resection, recurrence occurred in 79 (26%) of patients. For stage I and II disease, 5-year RFS rates were 90% and 43%, whereas 5-year DSS rates were 98% and 86% (P < 0.0001 and P = 0.0038, respectively). For grades 1, 2, and 3 disease, 5-year RFS rates were 87%, 49%, and 18%, and 5-year DSS rates were 98%, 89%, and 51% (P < 0.0001 for both). Stage II, grade 2, and grade 3 disease were each associated with increased recurrence and disease-specific death. CONCLUSIONS: Stage and grade are important prognostic factors that should be utilized to tailor postsurgical surveillance after curative resection of PanNET.

Factor VIII-Related Antigen Detects Phenotypic Change of Sinusoidal to Vascular Endothelium in Hepatic Fibrosis of Elderly Cadavers.

In advanced stages of hepatic fibrosis, the liver sinusoidal endothelium transforms to vascular endothelium with accompanying expression of factor VIII-related antigen (FVIIIRAg), a phenotypic marker of vascular endothelial cells. Liver fibrosis has been shown to be associated with aging and was found to be prevalent in elderly cadavers. Using immunohistochemistry, we studied FVIIIRAg expression in the livers of elderly cadavers with progressive stages of fibrosis. The vascular endothelium of portal tracts and central veins was stained for FVIIIRAg, providing an internal positive control. The incidence of FVIIIRAg expression was low in the sinusoids of livers that showed minimal fibrosis or perisinusoidal fibrosis but was increased in livers with advanced fibrosis (i.e., septa formation, bridging fibrosis, and cirrhosis). FVIIIRAg positive sinusoidal endothelial cells were distributed in loose aggregates in the periportal, periseptal, and midlobular parenchyma and were found less frequently in the centrilobular area. FVIIIRAg immune deposits appeared patchy and discontinuous along the sinusoidal lining, likely representing focalized transformation of sinusoidal to vascular endothelium. There was a discrete localization of FVIIIRAg immunoreactivity in the foci of severe parenchymal fibrosis. Conclusion. FVIIIRAg is a reliable marker for detecting the transformation of sinusoidal to vascular endothelium in advanced liver fibrosis in elderly cadavers.